Cretaceous Antodicranomyia (Diptera: Limoniidae) and their paleohabitat

New representatives of the Cretaceous cranefly genus Antodicranomyia (Diptera: Limoniidae) are reported from Albian-Cenomanian Charentese (French) amber. The newly reported specimens allow for an emended diagnosis of the type species A. azari, as well as the description of a new species, Antodicranomyia rubra sp. nov., which is mostly distinguished from the type species by features of its wing venation, antennae, and genitalia. As a rare, extinct genus known only from French amber, Antodicranomyia is compared with its closest relative genera Antocha, Dicranomyia and Antohelia. The evolutionary implications and paleohabitat of Antodicranomyia are discussed. The new discovery adds to the knowledge of the crane flies’ diversity and evolution in the mid-Cretaceous.

. Geographical and geological setting of the Cretaceous Charentese amber deposits (modified from Perrichot et al. 27 ). (A) simplified geological map with indication of amber localities; (B) synthetic regional stratigraphic section with indication of amber outcrops. Red dots and stars denote the outcrops yielding Antodicranomyia species considered in the present study. Diagnosis. Wing 3.5 × as long as wide; tip of Sc distad sc-r subequal to sc-r in length; r-m nearly aligned to the basal deflection of M 1+2 ; tip of R 3+4 upcurved; basal part of R 5 curved, 3 × as long as crossvein r-m; crossvein m-cu before fork of Mb; vein M 3 longer than d-cell; distance between tips of R 5 and R 3+4 approximately twice the distance between M 1 and R 5 ; distance between tips of R 1 and R 3+4 approximately 1.5 × the distance between R 3+4 and R 5 ; male genitalia with lobe (branch I = ventral gonostylus) and clasper (branch II = dorsal gonostylus) of gonostyli elongate, approximately 7 × as long as wide, narrowed, longer than half the length of gonocoxite; gonocoxite 3 × as long as wide; clasper strongly sclerotized, slightly broadened distally, bearing one thick apical seta-like spine; lobe longer than clasper, armed with two apical setae, pale, not very wide.
Remark. Such features like the rostrum distinctly shorter than head, the male antenna with 13 flagellomeres, the wing with Sc ending beyond the origin of Rs and veins r-r and r-m nearly aligned, the male genitalia with narrow lobe and clasper of gonostyli, additionally with the clasper strongly sclerotized, warrant placement of the new species in the genus Antodicranomyia as defined by Perrichot et al. 23 .
Etymology. The specific name is from the Latin rubra meaning red, and refers to 'La Montée Rouge' (the red slope), name of the access road to the type locality in Cadeuil.
Description (male). Body (Fig. 4A) pale brown, 4.30 mm long, with dark brown head. Head (Fig. 4A, B) 0.42 mm long, with moderately large, oval, almost holoptic, glabrous eyes; many strong, thick and comparatively short setae on occiput and vertex; rostrum distinctly shorter than head; antenna (Figs. 3A, 4A, B, E) 1.10 mm long, 15-segmented, shorter than head and thorax combined; scape elongate, cylindrical, massive, narrower than other segments of antenna; pedicel short, shorter and wider than scape, approximately as long as wide, widened in midlength; flagellomeres rather short and wide, becoming progressively slender toward antennal tip; flagellomeres 1-7 approximately as long as wide, 8-15 approximately twice as long as wide; last flagellomere longer than penultimate one. Antenna with few moderately elongate setae, Remark. The specimen is well preserved, although missing apical portions of some legs.
Comparison. The new species differs from A. azari mainly by the male genitalia with more elongate, narrowed clasper and lobe. In A. rubra sp. nov., the clasper is approximately 7 × as long as wide and is longer than half the length of gonocoxite, while in A. azari the clasper is at most 3 × as long as wide, shorter than half the length of gonocoxite. Both species also differ by the wing venation: vein sc-r is subequal to the tip of Sc in A. rubra sp. nov., one third the tip of Sc in A. azari; r-m is nearly aligned to the basal deflection of M 1+2 in A. rubra sp. nov., but nearly oblique to the basal deflection of M 1+2 in A. azari; the tip of R 3+4 and basal part of R 5 are curved, with basal part of R 5 3 × as long as r-m in A. rubra sp. nov., vs. tip of R 3+4 straight or at most weakly upcurved and basal part of R 5 just slightly arched and twice to three times as long as r-m in A. azari. A feature of the wing vein which makes it easy to distinguish between both species is the position of crossvein m-cu: in A. rubra sp. nov. this vein is anteriad fork of Mb, while it is aligned with fork of Mb in A. azari. Moreover, M 3 is distinctly longer than d-cell in the new species, but as long as or only slightly longer than d-cell in A. azari.

Discussion
As reflected by Perrichot et al. 23 in their selection of the genus name, Antodicranomyia shares features with the extant genera Antocha Osten Sacken 14 and Dicranomyia Stephens 28 . Antocha currently comprises 161 extant species within three subgenera Antocha, Orimargula Mik 29 , and Proantocha Alexander 4,30 , while only two extinct species left unclassified in subgenus are known 31,32 . Dicranomyia is represented by over 1150 extant species   [36][37][38] . As suggested by Perrichot et al. 23 , Antodicranomyia and Antocha are very similar in their male gonostyli, but Antodicranomyia differs by its long, sclerotized aedeagus and (from almost all subgenera of Antocha) by its narrow lobe of gonostylus. The wide anal area on the wing of Antodicranomyia distinguishes this genus from Caenoglochina. Some species of this subgenus similarly have narrow lobes of gonostyli, however these are broader and apically truncate, in most of Dicranomyia lobe (outer gonostylus) of gonostyli is ballon-like with rostral prolongation, clasper (inner gonostylus) is strongly sclerotized, hooked 39 . The male genitalia with two elongate gonostyli are characteristic for Antochini, but Antodicranomyia differs from this tribe by its wing venation which is characteristic of the Limoniini. The wing of Antocha is characteristicaly wide with almost square-shaped anal lobe, in Antodicranomyia anal lobe is well developed, but not so expressive as in Antocha 40 . The 15-segmented antennae of Antodicranomyia are intermediate between the 14-segmented ones of Limoniini and the 16-segmented ones of Antochini and could suggest a tendency to the reduction of antennal segments within this tribes 23 .
The history of Antodicranomyia somewhat parallels that of Antohelia Kania 39 . Antodicranomyia shares some features with Antocha and Dicranomyia, two extant genera with a long temporal range (since the mid-Cretaceous for Antocha, the Paleocene for Dicranomyia), while Antodicranomyia is restricted to the mid-Cretaceous French amber (Fig. 6).
Antohelia similarly shares some features with Antocha and Helius, two genera that are known since the Cretaceous 16

Material and methods
The Charente-Maritime and Charente departments of south-western France comprise several Early-Late Cretaceous deposits of fossil resin known under the collective name Charentese amber (Fig. 1A). The present study is based on inclusions in amber from the Archingeay 1 (Arc 1) and Cadeuil 2 (Cdl 2) deposits, as defined by Perrichot et al. (2010: figs. 1, 2) 27 . Now filled up with water forming lakes, both sites are former quarries that each exposed two lignitic, amber-bearing layers within sand and clay beds (Fig. 1B). The geological setting of the deposits have been detailed elsewhere 26,27,41 . The amber bed considered herein for Arc 1 was assigned to the 'lithological subunit A1' and dated as latest Albian or earliest Cenomanian based on palynomorph evidence 40,42,43 . Cdl 2 was assigned to the lithological subunit A2 which was similarly dated as Early Cenomanian 40 . A new male specimen of Antodicranomyia azari is reported in amber from the Archingeay deposit (Arc 1), which already yielded the type material of this species described in 2007 23 . And the male of a new species is reported from the Cadeuil deposit (Cdl 2). All specimens newly reported herein are deposited in the Geological Department and Museum of the University of Rennes (IGR), France. The specimens were examined using a Nikon SMZ 1500 stereomicroscope equipped with a Nikon DS-Fi1 camera. The measurements were taken with NIS-Elements D 3.0 software. The length of head was measured as the length of the head capsule. Measurements of the discal cell were taken from the proximal to distal ends of the d-cell; measurements of the vein M 3 were taken from the point of connection of vein m-m with vein M 3 to the margin of wing; the length of genitalia was measured from the posterior margin of tergite IX to the apex of gonocoxite. Drawings and photographs were made by Iwona Kania-Kłosok, with line drawings traced from the photographs. Terminology follows Krzemiński 1 for the wing venation nomenclature, and Ribeiro 46 or Perrichot et al. 23 for the male genitalic nomenclature.